Field of Invention
The present invention relates to camera modules, and more particularly to a camera module and its molded circuit board assembly and molded photosensitive assembly, and manufacturing method thereof.
Description of Related Arts
A camera module is one of the indispensable components of an intelligent electronic device such as smartphone, camera, computer device, wearable device, and the like. With the continuous development of a variety of intelligent devices and their popularity, the camera module requirements are getting higher and higher.
In recent years, intelligent electronic devices have been developed by leaps and bounds, wherein the growing trend of the intelligent electronic devices is towards thinner and thinner, and the camera modules are required to adapt to such development. The camera module is required to be multi-functional, lightweight and small, so that electronic devices can be thinner while meeting the imaging requirements. Therefore, the camera module manufacturers continuously focus on designing and manufacturing camera modules which meet these requirements.
Molded packaging technology is an emerging packaging technology developed from the conventional COB (Chip on Board) packaging technology. As shown in FIG. 1A of the drawings, the concept of encapsulating a circuit board by a conventional integrated packaging technology is illustrated. In this structure, the encapsulation portion 1 is integrally encapsulated on a circuit board 2 and a photosensitive chip 3, and the electronic components on the circuit board and the lead wires for electrically connecting the chip and the circuit board are covered, so that the occupied space of the electronic components is reduced, the size of the camera module can be reduced, and the problem that the dust attached to the electronic component affecting the image quality of the camera module is solved.
Compared with the conventional holder-type COB packaging technology, this packaging technology has more advantages in theory. However, in a period of time, this packaging technology only stays in the theoretical or manual experimental stages, and fails to achieve very good and practical implement that has not been put into actual production for quantitative production. The reasons are following aspects.
Firstly, although the integral packaging technology in other large industrial areas such as semiconductor is a well-known technology, in the field of camera module, it is a new application. Different industries need to mold different objects with different problems. For example, the body of a smartphone becomes thinner and thinner, so that the thickness of the smartphone becomes thinner and thinner too. As a result, camera modules are also required to have such a relatively thin thickness, so that the overall thickness of the phone will not increase because of the camera modules. It is understandable that components of the camera module are manufactured in a relatively small size, so that the ideal structure of the camera module cannot be produced by conventional methods. In the above-described configuration, it is usually necessary to form a through-hole, which is usually designed to have a square shape extended vertically, in the encapsulation portion 1 to provide a light path for the photosensitive chip 3 on the circuit board 2. Theoretically speaking, this conceptual structure does not have much substantial defects, but it does fail to take various mass production factors into account. In other words, this technology is only in the manual test stage instead of being developed to be applied in actual mass production. More specifically, a molding mould is generally needed in the packaging technology, as shown in FIG. 1B and FIG. 1C of the drawings, wherein when a molding block 4 of an upper mould of the molding mould is in cubic shape, during a molding process, at the contacting position of the upper mould and the encapsulation portion 1, the upper mould may adversely affect the shape of the encapsulation portion 1, as the bottom of the upper mould is in sharp square shape, while the mould is detaching from the molding material and causes deformation of the encapsulation portion 1 such as forming flashes. In addition, when the upper mould is being pulled out and drafted away from the encapsulation portion 1, an outer side surface of the molding block 4 of the upper mould and the encapsulation portion 1 have a large frictional force therebetween that may cause damages to the encapsulation portion 1. The effect is likely to be negligible in an industry of molding a product with relatively large size, but in the camera module field which has a small size in precise configuration, it becomes a critical factor. Therefore, the vertical prismatic column shaped through-hole structure is feasible in theory but is not suitable for mass productions in practice.
Secondly, a camera module is an optical electronic device and light capturing is an important factor to determine the image quality. As shown in FIG. 1D of the drawings, in the conventional holder assembling manner, the holder 5 mounted on the circuit board is required to reserve a mounting space 6 for the electronic components. The mounting space 6 forms an indent space and increases the size of the camera module. However, after the light is captured, very little incident light will directly project to the inner wall of the holder, so that there is less being reflected from the inner wall of the holder that will not affect the imaging quality. As shown in FIG. 1E of the drawings, in comparison with the structure of the holder that no incident light through the lens with an incident angle is reflected by the holder, when the holder is replaced by the conventional cubic shaped encapsulation portion 1, the integral package structure causes the inner wall of the encapsulation portion 1 reflecting the incident light to the photosensitive chip 3 easily, that results in increasing the influence of stray light so that the imaging quality of the camera module is degraded. Accordingly, in the aspect of the optical imaging quality, such rectangular shaped through-hole configuration formed in encapsulation portion 1 is not suitable for utility application.
In addition, in order to assemble the encapsulation portion 1 into a camera module, it is necessary to mount a lens or a motor on the encapsulation portion 1, so that the encapsulation portion 1 is needed to meet a certain structural strength. Therefore, the shape of the encapsulation portion 1 is required to be designed in regard to various factors, including but not limited to the light flux, structural strength, light reflectivity, ease of demoulding, and damage prevention during demoulding. However, the structure of the conventional encapsulation portion 1 apparently failed to encounter all such factors under consideration.